# Opening Range Breakout

`D08-F07-A05` · Geometric Chart Patterns → Market Structure, Breakouts, and Regimes · archetype `record-transform` · difficulty 2/5 · verification **verified**

Full page: https://docs.thefintechbuilder.com/geometric-chart-patterns/market-structure-breakouts-and-regimes/opening-range-breakout/
Agent skill: `npx skills add IslamBaraka90/Fintech-Algorithms-Library` — https://docs.thefintechbuilder.com/guides/agent-skill/

## Install and import

```bash
npm install fintech-algorithms
```

```ts
import { openingRangeBreakout } from "fintech-algorithms/geometric-chart-patterns/market-structure-breakouts-and-regimes/opening-range-breakout";
```

## Signature

```ts
openingRangeBreakout(input)
```

Fixes the high and low of the session's first `opening_bars` bars and then tests every later close against that frozen range. Unlike the rolling breakout topics the level never moves once the opening range is set.

## Parameters

| Name | Type | Required | Notes |
| --- | --- | --- | --- |
| `input` | `TopicInput` | yes | `bars` is the required OHLCV history, strictly ordered by `timestamp` and on a single adjustment basis. `parameters.opening_bars` (default `5`, integer of at least 1) sets how many leading bars form the range; `period` (default `20`, integer of at least 2) is validated by the family but unused here. |

## Returns

`TopicResult`

`series` and `latest` carry `upper`, `lower`, `up_break` and `down_break`. The warm-up is `opening_bars` bars, so with the default `ready_at` is 5; `upper` and `lower` are then constant for the rest of the series.

## Warm-up

The first `opening_bars bars (5 by default)` positions are `null`. Indices 0 through `opening_bars - 1` are the range itself and stay null in all four series; emission starts at index `opening_bars`.

## Errors

- When `opening_bars` is supplied as a non-integer or as a value below 1 — throws Error
- When a bar's `high` or `low` is not a finite number — throws Error

## Complexity

Time `O(n × opening_bars)`, space `O(n)`.

## Worked example

Captured by running this function on the input its own test provides. Real output of real code — but not asserted against a published figure.

### Input

`input`:

```json
{
  "bars": [
    {
      "timestamp": "2024-01-02",
      "basis": "synthetic-unadjusted",
      "open": 100,
      "high": 101.45,
      "low": 98.695,
      "close": 100,
      "volume": 750000,
      "benchmark": 200
    },
    {
      "timestamp": "2024-01-03",
      "basis": "synthetic-unadjusted",
      "open": 101.49111452,
      "high": 103.38381693,
      "low": 100.05480022,
      "close": 101.78791214,
      "volume": 795117,
      "benchmark": 200.56326135
    },
    {
      "timestamp": "2024-01-04",
      "basis": "synthetic-unadjusted",
      "open": 102.45519048,
      "high": 104.6701838,
      "low": 100.91147007,
      "close": 102.9549389,
      "volume": 840234,
      "benchmark": 201.11020913
    }
  ],
  "parameters": {}
}
```

### Call

```ts
openingRangeBreakout(input)
```

### Returns

object with 9 fields: topic_id, title, state, ready, ready_at, series, latest, parameters, …

```json
{
  "topic_id": "D08-F07-A05",
  "title": "Opening Range Breakout",
  "state": "calculated",
  "ready": true,
  "ready_at": 5,
  "series": {
    "upper": [null, null, null, null, null, 105.01857496],
    "lower": [null, null, null, null, null, 98.695],
    "up_break": [null, null, null, null, null, false],
    "down_break": [null, null, null, null, null, false]
  },
  "latest": {
    "upper": 105.01857496,
    "lower": 98.695,
    "up_break": false,
    "down_break": false
  },
  "parameters": {},
  "diagnostics": {
    "causal": true,
    "input_count": 96
  }
}
```

## Verification and provenance

Tier: **verified** (via E).

The worked example below is the figure published in this algorithm's article, replayed and asserted by the test suite on every build. The arithmetic cannot drift without the build failing.

Both tiers guarantee the signature. Full explanation: https://docs.thefintechbuilder.com/guides/verification/

Generated from the docs.json payload shipped inside fintech-algorithms@0.13.0.
The signature and parameter list are checked against the compiled implementation at build time,
so a description that contradicts the code fails the build rather than reaching this file.

## Links

- Article (how it works, step by step): https://thefintechbuilder.com/geometric-chart-patterns/market-structure-breakouts-and-regimes/opening-range-breakout/
- Implementation source: https://github.com/IslamBaraka90/Fintech-Algorithms-Library/blob/main/src/geometric-chart-patterns/market-structure-breakouts-and-regimes/opening-range-breakout/impl.ts
- Package on npm: https://www.npmjs.com/package/fintech-algorithms
- Domain index for agents: https://docs.thefintechbuilder.com/geometric-chart-patterns/llms.txt